FTIR/ATR Spectroscopy Applied to the Rapid Determination of Chemical Oxygen Demand of Wastewater

Abstract

A directly rapid quantification method for chemical oxygen demand (COD) of wastewater was established by Fourier transform infrared (FTIR) spectroscopy combined with attenuated total reflection (ATR) technology and moving window partial least squares (MWPLS) method with changeable parameters. All samples were firstly divided into the calibration set and the prediction set. And then according to the predicion effect, the optimal model was selected, and the corresponding waveband, number of adopted wavenumbers, PLS factor, root mean squared error of predication (RMSEP), correlation coefficient of predication (RP) were 3152-1109 cm-1, 1060, 8, 21.5 mg/L, and 0.981 respectively, which was obviously superior to the optimal PLS model on the whole spectral collecting region. The result shows that FTIR/ATR spectroscopy can be applied to the rapid determination of COD of wastewater, and the waveband selected by MWPLS method with changeable parameters has higher signal to noise ratio, which can effectively improve the precision of the predictive model.